Contagious diseases such as tuberculosis or Severe Acute Respiratory Syndrome (SARS) for example, represent serious concerns to hospital personnel. Many hospitals have central air supply and ventilation systems, in which pathogens can easily mix with hospital air and spread to an entire building through the air ducts of the ventilation system of that building. Also, health-care personnel tending to an infectious patient are exposed to germs carried in a cough or in the exhaled air of that infectious patient. Health-care personnel are also exposed to germs that become airborne from even a slight air movement around the patient's bed. Therefore, health-care personnel and other non-infected patients in hospitals are exposed to relatively high risks of contracting contagious diseases.
It is therefore desirable to isolate an infectious patient in a separate room where the air from that room is filtered and sterilized before it is released into hospital air. However, it is not always feasible to isolate one or more rooms in an hospital and provide each room with its own air control and filtering system, as a preventive measure against the spread of germs.
Therefore, a number of portable sealable enclosures have been developed in the past. These portable enclosures can be deployed in a short time inside an hospital room, to cover an hospital bed and to isolate a patient.
A search in the prior art has yielded several documents disclosing examples of patient isolation modules developed by others. A first example of a patient isolation enclosure is illustrated in U.S. Pat. No. 3,601,031 issued to Kenneth Abel on Aug. 24, 1971. This document describes a portable cubicle which is deployed inside an hospital room. An hospital bed is mounted inside this cubicle. A blower and a HEPA™ filter are mounted along one wall of the cubicle, with the blower discharge opening being mounted near the head of the bed. The blower inlet and discharge louvers are separated from each other by a partition extending alongside the hospital bed. Filtered air is forced to travel over the patient, from head to toes, and around the partition, to return to the blower and to be re-circulated through the filter and back into the cubicle.
Another example of a patient isolation module is described in U.S. Pat. No. 4,129,122 issued to J. A. Dout et al. on Dec. 12, 1978. This document also discloses a sealable enclosure mounted inside an hospital room. A blower discharges clean air over the head of an hospital bed. Foul air is drawn outside the enclosure and back to the blower along the space between the sealable enclosure and the walls and ceiling of the hospital room.
In yet another example, U.S. Pat. No. 6,062,977 issued to S. W. Hague on May 16, 2000, describes a filtering unit mounted on a wall adjacent an hospital bed at the head of the bed. The filtering unit draws air from a region near the head of the bed to entrains contaminants arising from a patient's breathing zone. The potentially contaminated air is filtered, irradiated by UV light and then discharged into hospital air.
Although the air control and treatment systems of the prior art deserve undeniable merits, there continues to be a need for an air control system that can effectively remove potentially contaminated air from above and alongside an infectious patient laying in an hospital bed.